Construction of tunnels



H (No Model.) 2She'ets8heet 1.

. J. F. ANDERSON.

Construction of Tunnels.

No. 241,272. Patented May 10,1881.

WITNESSES W BY ATTORNEYS.

NlTED STATES PATENT OFFICE.

CONSTRUCTION OF TUNNELS.

SPECIFICATION forming part of Letters Patent No. 241,272, dated May 10, 1881.

Application filed February 28, 1881.

To all whom it may concern:

Be it known that I, J only I ANDERSON, of Jersey City, in the county of Hudson and State of New Jersey, have invented a new and useful Improvement in the Construction of Underground Tunnels, of which the following is a specification.

The object of my in vention is to facilitate the construction of underground tunnels,especially where the earth is composed of soft materials, such as sand and silt, and at the same time insuring greater safety for the men engaged in constructing such tunnels.

The invention consists in constructing and carryingforward in the earth, in advance of the main tunnel, a central tube or small tunnel havin g a metallic shell, which I term a pilot-tunnel, whereby the nature of the soil in advance of the main tunnel can be ascertained, and the earth at the heading, in part, be supported during the excavation of the main tunnel.

The invention further consists in extending the rear portion of the shell of the central or pilot tunnel back from the heading into the completed part of the main tunnel, and in using this shell as a temporary support for the walls and shell of the main tunnel during their erection, as will be more fully described hereinafter.

The invention further consists in constructing the central tube or pilot -tunnel of interchangeable pieces or sections, whereby the rear portions of the pilot-tunnel may be removed, carried forward, and joined to the fronteud of the pilot-tunnel as fast as the work advances,

as will be more fully set forth hereinafter.

The invention further consists in the combination of the various parts above mentioned, as hereinafter more fully described.

In the accompanying drawings, forming part of this specification, Figure l is a longitudinal sectional elevation of atunnel being constructed withmyimproved pilot-tunnel. Fig.2is acrosssectional elevation of the same. Fig. 3 is a crosssectional elevation of the joints of each section of the pilot-tunnel. Fig. 4 is a cross-sectional elevation of the joint of the plates forming the sections of the pilot-tunnel.

Similar letters of reference indicate corresponding parts.

The pilot-tunnel or central tube is preferably made with a circular cross-sectional elevation,

(No model.)

as this is strongest, but it may be square or polygon a1, and likewise the pilot-tunnel or central tube is preferable made of iron, but maybe made of wood.

I will now describe the preferred constructionthat is, with a circular cross-section and made of iron.

The pilot-tunnel or central tube A is made of a series of tubular-interchangeable sections, B B, which are formed of a series of interchangeable segmental plates, 0 O, of the length of the scction,and united by means of the angle-irons D D, riveted to the inner sides, along the longitudinal edges, which angle-irons are riveted or bolted to a longitudinal joint-plate, E, which projects a few inches from the outer surface of the pilot-tunnel. These plates E form longitudinal ribs on the outside of the pilot-tunnel.

Angle-irons Gr G, against which the angleirons D D abut, are fastened to the inner surface at the end of each section B, these angleirons G necessarily being circular. Bolts are passed through the vertical flanges of the adjoining a-ngle-irons G as secured to the sections B B, and through plates H, which project outward several inches from the outer surface of the pilot-tunnel, and form transverse ribs.

The struts or braces J rest against the pilot-tunnel, and support and brace the outer iron-shell, K, and the masonry L L of the main tunnel,and also support that part of the pilottunnel extending into the finished main tunnel.

With my improved pilot-tunnel or central tube a tunnel is constructed as follows A horizontal excavation is made exactly in the center of the heading of the main tunnel, and one section, B, composed of a series of interchangeable plates,O,is passed into this apperture, which has been made long enough to receive this section. Care must be taken to have this section precisely in the middle of the main tunnel. The earth at the front end of this pilot-tunnel or section is removed until there is an excavation large enough to admit a section, B, in front of the section already in place. The transverse rib-plates H are then fastened to the forward end of the section B already in place, and the plates 0 G are passed through this section, and are united in front of it to form another section, and in this manner the pilot-tunnel or central tube is carried forward and into the earth, care being taken to build this pilot-tunnel or central tube in such a manner that it will always be absolutely in the center of the main tunnel, as this pilot-tunnel serves as a guide in constructing the main tunnel, and is destined to facilitate the true and accurate construction of the arch of the main tunnel. The front end of the pilot-tunnel should always be from twenty-five to thirty feet in advance of the head of the main tunnel, and should be carried forward as rapidly as the head of the main tunnel is carried forward. The rear or inner end of the pilot-tunnel extends into the finished part of the main tunnel a distance of about twenty-five to thirty feet, and is supported and held by the radial struts J, which, in turn, support the casing or shell of the main tunnel during its construction. The earth at the heading of the main tunnel is inclined, as shown at M in Fig. 1, and as soon as it is removed on the top of the tunnel iron shell-plates K are placed against the wall of the tunnel, and are supported by braces or struts J, resting upon the pilot-tunnel A. At the bottom of the incline M the brick-work begins, and during its construction is also supported by the braces J J. The pilot-tunnel is stiff enough to bear the pressure of the front braces, J, and the front end of the pilot-tunnel has a good and firm bearin g into the earth of the heading. The rear end of the pilottunnel receives equal pressure from all sides by the radial braces, as it is supported by the braces, as stated. As the front ends of the pilot-tunnel and the head of the main tunnel advance the rear end of the pilottunnel is taken down, the interchangeable plates and angleirons are carried through the pilot-tunnel, and are used to construct a fresh section in front, and in this manner the rear end of the pilottunnel is taken down and the front end built up as the tunnel advances.

Some of the advantages of the within-described method of constructing underground tunnels with a pilot are the following: As the front end of the pilot-tunnel is from twentyfive to thirty feet in advance of the head of the main tunnel, the ground through which the main tunnel will have to pass can be explored, and if any leaks or breaks occur they can be stopped much better in the head of the pilot-tunnel than in the head of the main tunnel, and the laborers in the tunnel can be notified of the danger, and much better precautions taken for the safety and welfare of the persons employed in the tunnel. As the engineer always knows what kind of ground he will encounter in following up the pilot-tunnel with the main tunnel, he can provide himself to meet such difficulties'as may occur, and delay is thus avoided.

In making tunnels in soft material it has been customary heretofore to bank the head of the tunnel, upon which banks the braces supportiugthe tunnel-ceiling rested. The enormous pressure of these braces causes the banks to give way, and the head of the tunnel was continually caving in, and it was only with great diflicult-y that the head of the tunnel could be carried forward but if the pilot-tunnel is used the braces supporting the ceiling at the forward end of the tunnel do not rest on the inclined tunnel-heading, but on the pilot-tunnel, and there is no pressure on the tunnel-heading. The pilot-tunnel assists in pre venting the earth at the tunnel-head from caving in or sliding down, for the upper part of the earth rests on the pilottunnel, and the distance between the bottom of the pilot and the bottom of the main tunnel is not large enough to permit the earth to slide. As all the braces are radial ones they can be considerably shorter than the radius of the main tunnel, and consequently can be of much smaller cross-sec' tion, and can be more conveniently handled than the heavy cumbersome braces used with tunnel-shields or with a banked heading. This is a point of great importance, both in regard toeeconomy and in regard. to the labor in the tunnel.

The longitudinal ribs E stiffen the pilottunnel, and the transverse ribs H do not only stiffen the pilot-tunnel, but also form anchors to keep and anchor the pilot-tunnel or central tube in the heading of the main tunnel, for the enormous earth-pressure at the heading of the pilot-tunnel tends to force the pilot out of the heading into the finished tunnel. These ribs H also serve to prevent slides of the earth at the heading of the tunnel, and back slip of the central tube or pilot-tunnel is thus entirely avoided.

The core may be made solid, if desired, and must then be forced into the headingby hydraulic pressure, but it must not be inferred that I explore with a solid core. The walls are then temporarily braced from this solid core in the manner described.

Having thus fully described my invention, I claim as new and desire to secure by Letters Patent- 1. The improvement in the art of constructing underground tunnels which consists substantially in carrying forward in the earth, in advance of the main tunnel, in the central part of the heading thereof, a removable central tube or pilot-tunnel, as herein set forth, whereby the earth at the heading of the main tunnel will be supported and explored.

2. An improvement in constructing underground tunnels, which consists in partially supporting the earth which incloses the main tunnel at its heading, by means of a central tube inserted in the earth of said heading in advance of the main tunnel, as described.

3. The method herein-described of supportin g the central tube or pilot-tunnel, which consists in anchoring the front end of the said pilot-tunnel in the earth of the heading of the main tunnel, and carrying the rear portions of the pilot-tunnel on braces within the main tunnel, as set forth.

4. In the construction of underground tunnels, the method herein described ofsnpportin g the front portions of the main tunnel, which consists in bracing said portions upon the back or exterior of the central tube or pilot-tunnel, as set forth.

5. In the construction of underground tunnels, the combination, with the main tunnel and the earth heading thereof, of a central tube or pilot-tunnel, as herein shown and described.

6. In the construction of underground tunnels, a central tube or pilot-tunnel made, sub- JOHN F. ANDERSON.

Witnesses OSCAR F. (him, 0. SEDGwIcK. 

